Boom, Boom on the Range

Where endangered Sonoran pronghorn antelope play under the roar of U.S. Air Force jets on live-fire bombing exercises

"The thing about endangered species is once they're gone, they're gone. So you want to emphasize the highest level of management. Sonoran pronghorn have shown unique adaptions to the desert, and for that reason they're of some value to keep around and learn from."

Ever since a cluster of Sonoran pronghorn were found at High Explosive Hill, the gray hillock in the middle of the northern Growler Valley has become something of a mecca for far-flung biologists.

As soon as she realized what was happening, Cabeza Prieta ecologist Laura Thompson-Olais says, she began pestering biologists at Luke to do something. "I called and urged the people at Luke to actually assess the situation themselves," she recalls.

Notes from the August 29, 1995, multi-agency meeting of a committee known as the Sonoran Pronghorn Core Working Group provide the first written record of a problem at H.E. Hill: "Pronghorn were documented using water at HE (high explosive) hill 1-2 times/day during daylight hours. Approximately 15 different individuals were observed using this water . . . Pronghorn adults were documented chasing coyotes away from the waterhole."

Depending on who's estimating, 15 Sonoran pronghorn could account for up to 20 percent of the entire U.S. population.

The first evidence of what would be a grudging Air Force response to the problem is contained in U.S. Fish and Wildlife Service documents, which indicate that someone from Luke's environmental office called Fish and Wildlife's Ecological Services Field Office in Phoenix on November 9, 1995, "regarding ongoing activity that may be affecting Sonoran pronghorn."

Thompson-Olais convened an emergency meeting at Luke on December 4, "because I was frustrated by the lack of action by everybody," she says, including her own agency, the Fish and Wildlife Service. (Her frustration persists.)

The Air Force's summary of the December 4 meeting indicates that filling or fencing the crater was discussed. Someone suggested that the Air Force consider establishing a new H.E. Hill site. Luke officials said that wouldn't be possible. Gary Blake, Luke's air space manager, suggested that the potential for harm to pronghorn is probably greater from strafing runs at other sites than from bomb drops at H.E. Hill.

The summary also notes that the first bombing mission at H.E. Hill each day "includes a 'dry' fly-by to ensure that no personnel are on the ground in the target areas. This may have the effect of alerting the pronghorn and causing them to move from the area."

On December 6, Captain M.S. Monroe, chief of Environmental Flight at Luke, wrote to Fish and Wildlife's Ecological Services supervisor in Phoenix, Sam Spiller, saying the Air Force intended to pursue "informal consultation" with the wildlife agency regarding pronghorn at H.E. Hill.

Spiller, whose office is responsible for ensuring that the Endangered Species Act is obeyed, responded on December 8. He provided a chronology of communications between Luke and his office, including the November phone call, during which, Spiller wrote, "We recommended two courses of action at the time. The first was that . . . an evaluation of all activities in the area, their actual effects on Sonoran pronghorn, and a resulting determination of effect should be made. The second was that if Sonoran pronghorn are currently being affected (e.g., if pronghorn were in actual danger of being disturbed) by ongoing activities, then something should be done immediately to eliminate those effects."

Spiller wrote that these recommendations were reiterated during the December 4 meeting at Luke.

Two months later, the Air Force apparently had done nothing to implement Spiller's suggestions.

The Core Working Group includes representatives of the Arizona Department of Game and Fish, U.S. Fish and Wildlife, Cabeza Prieta, Organ Pipe, Luke Air Force Base and the Yuma Marine Air Station. At the group's February 22 meeting, the pronghorns near H.E. Hill sparked lively discussion. The meeting notes indicate that Cabeza Prieta biologist Steve Henry asked Luke biologist Bob Barry, "If PH [pronghorns] are detected in the area, can an operation be aborted?"

Barry: "Big bucks are involved if a mission is scrubbed. It is difficult to scrub a mission when we don't know the risk to PH."

Henry: "If the area is closed, it might not be for a day. The site might need to be closed for weeks or months."

Barry: "Their [Air Force] people would not like doing that; no evidence that any animal has been killed."

Bill Austin, a biologist from the Fish and Wildlife Service, piped up, telling Barry: "You need to know the effects; you may be killing PH; you need to determine the risks."

Austin later told Barry: "ES [Ecological Services] sent a letter to Luke AFB in early December looking for specific measures to protect PH in the ranges. There has not been a response. Activity possibly killing PH. Luke should very well be very nervous and try to do whatever they can do something."

On March 4, after two months' hiatus for cleanup, the Air Force began a new season of bombing at H.E. Hill--despite the fact that during a March 3 monitoring flight three or four pronghorns were observed bedding down on H.E. Hill itself.

Air Force biologists say they were never told that the pronghorn were on H.E. Hill.

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